The two companies are part of the New York State Health Insurance Program (NYSHIP). NYSHIP provides coverage to active and retired state, participating local government and school district workers and their families.

In one of the audits, errors were found resulting in overpayments in 57% of claims reviewed.

"While most New Yorkers are watching their spending, (Empire) Blue Cross and Blue Shield and United HealthCare are not monitoring bills and are letting the state overpay health providers," said DiNapoli. "An error rate showing that nearly 6 out of every 10 claims are billed incorrectly is simply unacceptable and cannot continue. These companies have to do a better job watching taxpayer dollars."